A retroreflective material is a material that reflects light back to its source with a minimum of scattering. Retroreflective material may be used to increase the conspicuity of items such as traffic signs, license plates, parts of vehicles, obstructions, clothing etc., particularly at nighttime.
A camera may take a digital photograph of a scene to acquire a digital image. The scene may include a retroreflective object, i.e. an object having a retroreflective material. A processor may be configured to locate the object in the digital image. The processor may further be configured to identify features of the object in the digital image. The retroreflective properties of the object may cause the object to be more conspicuous in the digital image compared to the surrounding scene in the digital image. This may assist the processor in locating the object and/or identifying features of the object in the digital image.
For example, vehicle license plates are typically retroreflective. An automatic license plate recognition (ALPR) system may take a digital photograph of a vehicle to acquire a digital image, and then search for the license plate in the digital image. The ALPR system may further process the located license plate in the digital image in order to determine the symbols of the vehicle's license registration identifier. The retroreflective properties of the license plate may allow for the ALPR system to more easily locate the license plate in the digital image and/or more easily determine the vehicle's license registration identifier on the license plate.
As another example, street signs are typically retroreflective. An automatic recognition system on an autonomous vehicle may take a digital photograph of the scene in front of the vehicle to acquire a digital image, and then search for a traffic sign in the digital image. The system may further process a located traffic sign in the digital image in order to determine the information being conveyed by that traffic sign. The retroreflective properties of the traffic sign may allow for the system to more easily locate the traffic sign in the digital image and/or more easily determine the information being conveyed by the traffic sign.